[moderation] [ext4?] KCSAN: data-race in __mark_inode_dirty / generic_buffers_fsync_noflush (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 02adc1490e6d Merge tag 'spi-fix-v6.16-rc1' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17a15e0c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f437300db311c188
dashboard link: https://syzkaller.appspot.com/bug?extid=99f320539456d1fc35b8
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e50e82c70a27/disk-02adc149.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3744831c0ef7/vmlinux-02adc149.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7e2fbf67e791/bzImage-02adc149.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+99f320...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __mark_inode_dirty / generic_buffers_fsync_noflush

write to 0xffff888106b8a008 of 4 bytes by task 6326 on cpu 1:
__mark_inode_dirty+0x240/0x760 fs/fs-writeback.c:2558
generic_update_time fs/inode.c:2064 [inline]
inode_update_time fs/inode.c:2077 [inline]
__file_update_time fs/inode.c:2305 [inline]
file_modified_flags+0x324/0x350 fs/inode.c:2376
file_modified+0x17/0x20 fs/inode.c:2392
ext4_write_checks fs/ext4/file.c:279 [inline]
ext4_buffered_write_iter+0x1d0/0x3c0 fs/ext4/file.c:295
ext4_file_write_iter+0x383/0xf00 fs/ext4/file.c:-1
iter_file_splice_write+0x5f2/0x970 fs/splice.c:738
do_splice_from fs/splice.c:935 [inline]
direct_splice_actor+0x153/0x2a0 fs/splice.c:1158
splice_direct_to_actor+0x30f/0x680 fs/splice.c:1102
do_splice_direct_actor fs/splice.c:1201 [inline]
do_splice_direct+0xda/0x150 fs/splice.c:1227
do_sendfile+0x380/0x650 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64 fs/read_write.c:1417 [inline]
__x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106b8a008 of 4 bytes by task 6307 on cpu 0:
generic_buffers_fsync_noflush+0x80/0x120 fs/buffer.c:614
ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
ext4_sync_file+0x1ab/0x690 fs/ext4/fsync.c:147
vfs_fsync_range+0x10d/0x130 fs/sync.c:187
generic_write_sync include/linux/fs.h:3027 [inline]
ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:305
ext4_file_write_iter+0x383/0xf00 fs/ext4/file.c:-1
iter_file_splice_write+0x5f2/0x970 fs/splice.c:738
do_splice_from fs/splice.c:935 [inline]
direct_splice_actor+0x153/0x2a0 fs/splice.c:1158
splice_direct_to_actor+0x30f/0x680 fs/splice.c:1102
do_splice_direct_actor fs/splice.c:1201 [inline]
do_splice_direct+0xda/0x150 fs/splice.c:1227
do_sendfile+0x380/0x650 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64 fs/read_write.c:1417 [inline]
__x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000 -> 0x00000028

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6307 Comm: syz.2.1031 Not tainted 6.16.0-rc1-syzkaller-00157-g02adc1490e6d #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.